Tag Archives: 4HRA peak
Following a hockey puck can be challenging. It moves really fast and it’s not always obvious what the next player is going to do. Wayne Gretzky famously said: “Skate to where the puck is going; not where it’s been”. The same analogy can be applied in most sports: football quarterbacks throw to where the receiver is going to be; not where they are. Your monthly 4-Hour Rolling Average (and resulting MLC) is also a moving target.
By now, many shops are using soft caps and/or taking advantage of special pricing offerings from IBM such as Mobile and zNALC. These are excellent ideas — but, as all performance and capacity professionals know, reducing one 4HRA bottleneck only creates another.
If you take advantage of IBM’s variable workload license charges (VWLC), you’re more than familiar with the challenges of keeping costs low. In all likelihood, due to the complexity of how the rolling-four-hour-average (R4HA) is calculated, you find out the good or bad news only after you get your bill. You probably have IMS, CICS, DB2 and more running in a variety of LPARs with demand fluctuating throughout the day. And even if you keep your eye on your monitors, looking at the online work may give you a false feeling of confidence about how well you’re managing.
When it was first introduced, IBM’s sub-capacity pricing was a boon for capacity planners from a financial standpoint—allowing them to be more proactive in their planning. In the pre-sub-capacity era, all upgrades had to be carefully managed because of the huge potential impact on software pricing. Now, you can right-size your hardware and worry less about software costs—until you hit a soft cap, that is.
When it comes to lowering your company’s Rolling 4-Hour Average (R4HA), is capping always your best option? As we’ve mentioned elsewhere, while sub-capacity pricing can immediately reduce software costs, most installations need a way to guarantee a limit to the monthly charges to experience substantial savings. IBM offers a number of ways to do this, but virtually all of them involve the notion of “capping”. Capping is incredibly beneficial in certain scenarios; but, it isn’t necessarily the best choice for every installation.
Is that ten-minute burst of CPU activity at market open driving up your software bill? What about that extremely busy hour yesterday afternoon? Well, it’s possible—but these instances also might not make an impact at all. As we’ve mentioned in various posts, software license fees under IBM’s sub-capacity pricing model are determined according to the Rolling 4-Hour Average (R4HA). Since the R4HA is literally an average over four hours, it takes a long time to rise and a long time to fall. Further, it may not recur at the same day or time every month.